The petroleum industry is increasingly turning to coal, tar sands, heavy crudes and distilled residual oils as sources for feedstocks. Feedstocks derived from these heavy materials often contain more sulfur and nitrogen than feedstocks derived from more conventional crude oils. They are commonly referred to as being dirty feeds. These feeds require a considerable amount of upgrading before being introduced into processes which make lighter products such as fuel oil or gasoline. Such upgrading or refining generally is accomplished by the hydrotreating processes which are well known in the petroleum industry.
Hydrotreating processes may require the step of treating the hydrocarbon with hydrogen and usually a catalytic material to hydrogenate aromatics and other unsaturates to form aliphatic compounds, or to remove unwanted components or compounds such as nitrogen or sulfur bearing compounds, or to convert unwanted components into innocuous or less undesirable compounds. Hydrotreating may be applied to a wide variety of feedstocks, e.g., solvents; light, middle or heavy distillate feeds and residual feeds; or fuels. In hydrorefining relatively light feeds, the feed are treated with hydrogen often to improve odor, color, stability, or combustion characteristics. Unsaturated hydrocarbons are often hydrogenated to saturation. Sulfur- and nitrogen-bearing compounds are occasionally removed as part of such treatments. In the treatment of catalytic cracking feedstocks, the cracking quality of the feedstock is generally improved by a prior hydrotreating step such that elemental carbon yield is reduced and gasoline yield is increased. In the hydrodesulfurization ("HDS") of heavier feedstocks, or residua, the sulfur compounds are hydrogenated and cracked. Carbon-sulfur bonds are broken, and the sulfur, for the most part, is converted to hydrogen sulfide which is removed in gaseous form from the process. Hydrodenitrogenation ("HDN"), to some degree, also accompanies hydrodesulfurization reactions.
Catalysts which are most commonly used for hydrotreating reactions include materials such as cobalt molybdate on alumina, nickel on alumina, cobalt molybdate promoted with nickel, nickel tungstate, etc. Molybdenum sulfide is also widely used to upgrade oils containing sulfur and nitrogen compounds by catalytically removing such compounds in the presence of hydrogen.
The use of various rhenium and sulfur containing catalysts in the hydrodesulfurization of heavy feedstocks is known. For instance, U.S. Pat. No. 3,663,431, to Wagner, issued May 16, 1972, suggests the use of rhenium disulfide as a catalyst in the HDS of various heavy hydrocarbons. U.S. Pat. Nos. 4,308,171 and 4,368,115 suggest nonaqueous preparations of rhenium sulfides and that rhenium sulfides may be suitable as HDS catalysts.
U.S. Pat. No. 4,299,892 discloses a layeredsheet configuration of dichalcogenides of Group IVb, Vb, molybdenum, and tungsten.
U.S. Pat. No. 3,509,213 discloses a rhenium sulfide catalyst useful in the reductive alkylation of aromatic amino and nitro compounds.
None of these references show ReS.sub.2+x where x is &gt;0 and .ltoreq.2 and where the materials have a specific surface area of 40 m.sup.2 /gm or greater and are amorphous to X-ray. None of the catalysts of these references is prepared by the aqueous preparation of the catalyst of the present invention or has an HDS activity as high as does the catalyst of the invention.